Amany M. Fekry

Nano-TiO2 modified carbon paste sensor for electrochemical nicotine detection using anionic surfactant

A newly competitive electrochemical sensor for nicotine (NIC) detection was successfully achieved. Nano-TiO2 with a carbon paste electrode (CPE) were used for the sensor construction, where Nano-TiO2 was considered as one of the richest and highly variable class of materials. The sensor showed electrocatalytic activity in both aqueous and micellar media toward the oxidation of NIC at Britton-Robinson (B-R) buffer solution (4×10(-2)M) of pH range (2.0-8.0) containing (1.0mM) sodium dodecylsulfate (SDS) using cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) techniques. Scanning electron microscope (SEM) and Energy Dispersive X-Ray Analysis (EDX) techniques were also used. The linear range of detection for NIC using the new Nano-TiO2 Modified Carbon Paste sensor (NTMCP) was detected using diffrential pulse voltammetry (DPV) technique and it was found between 2×10(-6)M and 5.4×10(-4)M with a detection limit of 1.34×10(-8)M. The obtained results clarified the simplicity, high sensitivity and selectivity of the new NTMCPE for nicotine determination in real cigarettes and urine samples.

A new simple electrochemical Moxifloxacin Hydrochloride sensor built on carbon paste modified with silver nanoparticles

A new sensitive simple electrochemical sensor for Moxifloxacin Hydrochloride (MOXI) detection has been successfully performed. The sensor built on carbon paste (CP) modified with silver nanoparticles (AgNPs). AgNPs are biocompatible stable noble materials especially in biological sensing. The silver nanoparticles modified carbon paste electrode (SNMCPE) displayed high electrocatalytic activity towards oxidation of 1.0mM MOXI in Britton Robinson (BR) buffer of pH range (2.0-9.0). The techniques used to do this work are cyclic voltammetry (CV), linear sweep voltammetry (LSV), chronoamperometry (CA) and electrochemical impedance spectroscopy (EIS). Surface characteristics were achieved using scanning electron microscopic (SEM) and Energy Dispersive X-Ray Analysis (EDX) techniques. The effect of changing MOXI concentration (7.0×10-7 to 1.8×10-4M) was studied in BR buffer (pH =7.4) at a scan rate of 50mV/s using SNMCPE. The detection and quantification limits were found to be 2.9×10-9M and 9.6×10-8M, respectively. In order to assess the applicability of MOXI detection method in real samples; this method was tested in Delmoxa tablet and human urine sample. Good sensible results were attained for MOXI detection.

Electrochemical design of a new nanosensor based on cobalt nanoparticles, chitosan and MWCNT for the determination of daclatasvir: a hepatitis C antiviral drug

Daclatasvir (DAC) is listed on the World Health Organizations list of essential medicines needed in a basic health system, therefore, electrochemical and impedance spectroscopic methods are necessary to obtain information about its mechanism using a carbon paste electrode (CPE) modified with chitosan (Cs)/multi-walled carbon nanotubes (CNT) and cobalt nanoparticles (CoNps). The simultaneous determination of DAC with the hepatitis B antiviral drug entecavir (ENT) was also investigated by differential pulse voltammetry in universal buffer pH 2.0. The experimental results specify a linear relation between the DAC peak current and its concentration in the range from 1.0 nM to 12 μM, leading to a detection limit of 8.82 × 10−10 M. Finally, this novel sensor was successfully used to determine DAC in human biological fluids such as urine, blood serum and in pharmaceutical formulations.

Electrochemical behavior of a novel nano-composite coat on Ti alloy in phosphate buffer solution for biomedical applications

A novel nano-composite film coat of organic/inorganic composition including chitosan (CS), TiO2 nanoparticles (TO) and hydroxyapatite (HA) nanoparticles, was synthesized on a Ti–6Al–4V alloy surface. Open-circuit potential (OCP), electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization measurements were used to observe the corrosion behavior of the novel synthesized nano-composite coat on titanium alloy surface in a phosphate buffer solution. The results were confirmed by scanning electron microscopy (SEM) and energy dispersive X-ray (EDX) analysis techniques. The antibacterial activity for the novel nano-coat was determined and compared with the bare Ti alloy. Electrochemical impedance spectroscopy measurements showed that the total corrosion resistance of this newly synthesized nano-coat gave the highest corrosion resistance compared to the separate CS, TO and/or HA coatings. Also, this novel nano-coat showed high antibacterial activity compared with the bare alloy. The excellent biocompatibility of this novel nano-coat may be due to its organic/inorganic composition.

A novel electrochemical nicotine sensor based on cerium nanoparticles with anionic surfactant

A novel promising electrochemical nicotine (NIC) sensor was prepared by electrodeposition of Ce-nanoparticles on a carbon paste electrode (CPE). Electrochemical techniques including cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), scanning electron microscope (SEM) and Energy Dispersive X-ray Analysis (EDX) techniques, in both aqueous and micellar media were used. NIC measurements were investigated in Britton–Robinson (B–R) buffer solutions with a pH range (2.0–8.0) containing (1.0 mM) sodium dodecyl sulfate (SDS). The linear response range of the sensor was between 4 × 10−6 M and 5 × 10−4 M with a detection limit of 9.43 × 10−8 M. Good results were achieved for the detection of NIC in real samples and with different brands of commercial cigarettes.

Antimicrobial ruthenium complex coating on the surface of titanium alloy. High efficiency anticorrosion protection of ruthenium complex.

A ruthenium complex was prepared and structurally characterized using various techniques. Antibacterial and antifungal activities of ruthenium complex were evaluated. High significant antimicrobial activity against Escherichia coli, Staphylococcus aureus and Candida albicans was recorded. Minor cytotoxicity records were reported at the highest concentration level using MTT assay. The influence of Cu(II), Cr(III), Fe(III) and Ru(III) metal ions of salen Schiff base on the corrosion resistance of Ti-alloy in 0.5M HCl was studied. In vitro corrosion resistance was investigated using electrochemical impedance spectroscopy (EIS) measurements and confirmed by surface examination via scanning electron microscope (SEM) technique. Both impedance and phase angle maximum (θ(max)) values were at maximum in the case of the ruthenium complex with promising antibacterial and antifungal activities. The surface film created by the ruthenium complex was highly resistant against attack or deterioration by bacteria. The EIS study showed high impedance values for the ruthenium complex with increasing exposure time up to 8 days. SEM images showed uniform distribution and adsorption of Ru(III) ions on Ti-alloy surface. The ruthenium complex, as a model of organic-inorganic hybrid complex, offered new prospects with desired properties in industrial and medical applications.

The application of a bee glue-modified sensor in daclatasvir dual effect detection

A simple and novel carbon paste sensor containing chemically mixed propolis (bee glue) and graphene oxide (GO) was prepared, then electrochemical deposition of silver nanoparticles (AgNPs) was performed to fabricate a selective and sensible electrochemical sensor to detect Daclatasvir (DAC). This drug was newly approved in July 2015 as an essential medicine for Hepatitis C in the USA. A limited study was performed on this drug. The modified synthesized sensor has been characterized by scanning electron microscopy (SEM), energy dispersive X-ray (EDX) analysis and electrochemical experiments. The SNMGOPE (silver nanoparticles modified graphene oxide carbon paste electrode) gives a high electrocatalytic activity for 1.0 mM DAC oxidation in Britton Robinson (BR) buffer of pH = 2.0. The change in DAC concentration (2.5 × 10−8 to 1.2 × 10−5 M) was investigated against current, at 10 mV s−1, using differential pulse voltammetry (DPV), giving a detection limit of 1.599 nM. Improvement in the electron transfer process and a decrease in charge transfer resistance were detected. This created a sensor that effectively analyzes DAC concentration in real samples, such as pharmaceutical formulations and human urine samples.

Electrochemical Corrosion Behavior of Magnesium Alloys in Biological Solutions

Magnesium (Mg) is the fourth most abundant cation in the human body [Fekry & El-Sherief, 2009]. It is very abundant in the Earth being considered the fourth highest, following iron, oxygen and silicon. The raw ores of Mg are dolomite (MgCO3.CaCO3) and magnesite (MgCO3), and Mg is the second most abundant metal in seawater following sodium. It is therefore a comparatively low cost material. Magnesium is the lightest of all metals in practical use, and has a density (1.74 g cm-3) of about two thirds of aluminum and only one quarter that of iron. Pure magnesium metal has useful properties such as shielding against electromagnetic waves, vibration damping, dent resistance, machinability and low toxicity in humans, in addition to its recyclability as it has a lower specific heat and a lower melting point than other metals. On the other hand, magnesium has shortcomings such as insufficient strength, elongation and heat resistance as well as being subject to corrosion. To put Mg to practical use, it is necessary to deal with its shortcomings and improve its performance through alloying with various elements. Alloying magnesium improves its strength, heat resistance and creep resistance (creep is defined as deformation at a high temperature and under load). However, the addition of alloying elements modifies the corrosion behavior of magnesium in such a way that it can be beneficial or deleterious. Some advantages of magnesium alloys are their high stiffness-to-weight ratio, great ease of machinability, good casting qualities suitable for high pressure die-casting, high damping capacity and good weldability under controlled atmosphere. Magnesium can form intermetallic phases with most alloying elements, the stability of this phase increases with the electronegativity of the other element [Kainer, 2003]. Aluminum (Al) had already become the most important alloying element for significantly increasing the tensile strength, specifically by forming the intermetallic phase Mg17Al12. Similar effects can be achieved with zinc (Zn) and manganese (Mn), while the addition of silver (Ag) leads to improve hightemperature strength. The identification of magnesium alloys is standardized worldwide in the ASTM norm; each alloy is marked with letters indicating the main alloy elements, followed by the rounded figures of each (usually two) weight in percentage terms. The last letter in each identification number indicates the stage of development of the alloy. However, according to the elemental composition two major magnesium alloy systems are available to the designer. The first includes alloys containing 2 – 10 wt% Al, combined with minor additions of zinc and manganese. These alloys are widely available at moderate cost,

Electrochemical behavior of surgical 316L stainless steel eye glaucoma shunt (Ex-PRESS) in artificial aqueous humor

A novel system of electrodeposited gold nanoparticles on a carbon paste electrode was utilized as an electrochemical sensor to monitor the corrosion performance of 316L stainless steel alloy in aqueous humor containing moxifloxacin hydrochloride (MFH) drug. Electrochemical impedance spectroscopy (EIS), cyclic voltammetry (CV) and potentiodynamic polarization measurements were used to estimate the corrosion performance of 316L stainless steel alloy in aqueous humor with immersion time. The experimental data was confirmed by scanning electron microscopy (SEM), Energy dispersive X-ray analysis (EDX) and antibacterial activity. All techniques conform well to each other and confirmed that the tested alloy corrosion decreases with increasing immersion time in aqueous humor. Corrosion is more inhibited after the addition of MFH drug. In addition, as the concentration of the drug increases, the protection efficiency of the tested alloy increases. This behavior was confirmed by sensing the drug concentration with time using the modified carbon paste electrode.

A novel simple biosensor containing silver nanoparticles/propolis (bee glue) for microRNA let-7a determination

A novel sensitive electrochemical sensor for microRNAlet-7a detection in normal serum samples, hepatocellular carcinoma patients and human liver cancer cells, has been excellently synthesized. The sensor constructed of carbon paste (CP) amended with silver nanoparticles (AgNPs) and extracted propolis (bee glue). The AgNPs/P modified carbon paste electrode (APCPE) displayed a high electrocatalytic activity in a Britton Robinson (BR) buffer (pH = 7.4). The techniques utilized to prepare this work are square wave voltammetry (SWV) and electrochemical impedance spectroscopy (EIS). Surface characteristics were achieved using scanning (SEM), Fourier-transform infrared spectroscopy (FTIR), Spectrophotometer, transmission (TEM) electron microscope, energy dispersive X-ray analysis (EDX) and elemental mapping (EM) techniques. Under optimal conditions, the suggested sensor exhibits good rapid and sensible response reaching a very low detection limit of 10-3 femtomolar.